diff options
Diffstat (limited to 'arch/cris/arch-v10/kernel/time.c')
| -rw-r--r-- | arch/cris/arch-v10/kernel/time.c | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/arch/cris/arch-v10/kernel/time.c b/arch/cris/arch-v10/kernel/time.c new file mode 100644 index 000000000..b5eb5cd2f --- /dev/null +++ b/arch/cris/arch-v10/kernel/time.c @@ -0,0 +1,267 @@ +/* + * linux/arch/cris/arch-v10/kernel/time.c + * + * Copyright (C) 1991, 1992, 1995 Linus Torvalds + * Copyright (C) 1999-2002 Axis Communications AB + * + */ + +#include <linux/timex.h> +#include <linux/time.h> +#include <linux/jiffies.h> +#include <linux/interrupt.h> +#include <linux/swap.h> +#include <linux/sched.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <asm/types.h> +#include <asm/signal.h> +#include <asm/io.h> +#include <asm/delay.h> +#include <asm/irq_regs.h> + +/* define this if you need to use print_timestamp */ +/* it will make jiffies at 96 hz instead of 100 hz though */ +#undef USE_CASCADE_TIMERS + +unsigned long get_ns_in_jiffie(void) +{ + unsigned char timer_count, t1; + unsigned short presc_count; + unsigned long ns; + unsigned long flags; + + local_irq_save(flags); + timer_count = *R_TIMER0_DATA; + presc_count = *R_TIM_PRESC_STATUS; + /* presc_count might be wrapped */ + t1 = *R_TIMER0_DATA; + + if (timer_count != t1){ + /* it wrapped, read prescaler again... */ + presc_count = *R_TIM_PRESC_STATUS; + timer_count = t1; + } + local_irq_restore(flags); + if (presc_count >= PRESCALE_VALUE/2 ){ + presc_count = PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2; + } else { + presc_count = PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2; + } + + ns = ( (TIMER0_DIV - timer_count) * ((1000000000/HZ)/TIMER0_DIV )) + + ( (presc_count) * (1000000000/PRESCALE_FREQ)); + return ns; +} + +static u32 cris_v10_gettimeoffset(void) +{ + u32 count; + + /* The timer interrupt comes from Etrax timer 0. In order to get + * better precision, we check the current value. It might have + * underflowed already though. + */ + count = *R_TIMER0_DATA; + + /* Convert timer value to nsec */ + return (TIMER0_DIV - count) * (NSEC_PER_SEC/HZ)/TIMER0_DIV; +} + +/* Excerpt from the Etrax100 HSDD about the built-in watchdog: + * + * 3.10.4 Watchdog timer + + * When the watchdog timer is started, it generates an NMI if the watchdog + * isn't restarted or stopped within 0.1 s. If it still isn't restarted or + * stopped after an additional 3.3 ms, the watchdog resets the chip. + * The watchdog timer is stopped after reset. The watchdog timer is controlled + * by the R_WATCHDOG register. The R_WATCHDOG register contains an enable bit + * and a 3-bit key value. The effect of writing to the R_WATCHDOG register is + * described in the table below: + * + * Watchdog Value written: + * state: To enable: To key: Operation: + * -------- ---------- ------- ---------- + * stopped 0 X No effect. + * stopped 1 key_val Start watchdog with key = key_val. + * started 0 ~key Stop watchdog + * started 1 ~key Restart watchdog with key = ~key. + * started X new_key_val Change key to new_key_val. + * + * Note: '~' is the bitwise NOT operator. + * + */ + +/* right now, starting the watchdog is the same as resetting it */ +#define start_watchdog reset_watchdog + +#ifdef CONFIG_ETRAX_WATCHDOG +static int watchdog_key = 0; /* arbitrary number */ +#endif + +/* number of pages to consider "out of memory". it is normal that the memory + * is used though, so put this really low. + */ + +#define WATCHDOG_MIN_FREE_PAGES 8 + +void reset_watchdog(void) +{ +#if defined(CONFIG_ETRAX_WATCHDOG) + /* only keep watchdog happy as long as we have memory left! */ + if(nr_free_pages() > WATCHDOG_MIN_FREE_PAGES) { + /* reset the watchdog with the inverse of the old key */ + watchdog_key ^= 0x7; /* invert key, which is 3 bits */ + *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) | + IO_STATE(R_WATCHDOG, enable, start); + } +#endif +} + +/* stop the watchdog - we still need the correct key */ + +void stop_watchdog(void) +{ +#ifdef CONFIG_ETRAX_WATCHDOG + watchdog_key ^= 0x7; /* invert key, which is 3 bits */ + *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) | + IO_STATE(R_WATCHDOG, enable, stop); +#endif +} + + +extern void cris_do_profile(struct pt_regs *regs); + +/* + * timer_interrupt() needs to keep up the real-time clock, + * as well as call the "xtime_update()" routine every clocktick + */ +static inline irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + struct pt_regs *regs = get_irq_regs(); + /* acknowledge the timer irq */ + +#ifdef USE_CASCADE_TIMERS + *R_TIMER_CTRL = + IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) | + IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) | + IO_STATE( R_TIMER_CTRL, i1, clr) | + IO_STATE( R_TIMER_CTRL, tm1, run) | + IO_STATE( R_TIMER_CTRL, clksel1, cascade0) | + IO_STATE( R_TIMER_CTRL, i0, clr) | + IO_STATE( R_TIMER_CTRL, tm0, run) | + IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz); +#else + *R_TIMER_CTRL = r_timer_ctrl_shadow | IO_STATE(R_TIMER_CTRL, i0, clr); +#endif + + /* reset watchdog otherwise it resets us! */ + reset_watchdog(); + + /* Update statistics. */ + update_process_times(user_mode(regs)); + + /* call the real timer interrupt handler */ + xtime_update(1); + + cris_do_profile(regs); /* Save profiling information */ + return IRQ_HANDLED; +} + +/* timer is IRQF_SHARED so drivers can add stuff to the timer irq chain */ + +static struct irqaction irq2 = { + .handler = timer_interrupt, + .flags = IRQF_SHARED, + .name = "timer", +}; + +void __init time_init(void) +{ + arch_gettimeoffset = cris_v10_gettimeoffset; + + /* probe for the RTC and read it if it exists + * Before the RTC can be probed the loops_per_usec variable needs + * to be initialized to make usleep work. A better value for + * loops_per_usec is calculated by the kernel later once the + * clock has started. + */ + loops_per_usec = 50; + + /* Setup the etrax timers + * Base frequency is 25000 hz, divider 250 -> 100 HZ + * In normal mode, we use timer0, so timer1 is free. In cascade + * mode (which we sometimes use for debugging) both timers are used. + * Remember that linux/timex.h contains #defines that rely on the + * timer settings below (hz and divide factor) !!! + */ + +#ifdef USE_CASCADE_TIMERS + *R_TIMER_CTRL = + IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) | + IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) | + IO_STATE( R_TIMER_CTRL, i1, nop) | + IO_STATE( R_TIMER_CTRL, tm1, stop_ld) | + IO_STATE( R_TIMER_CTRL, clksel1, cascade0) | + IO_STATE( R_TIMER_CTRL, i0, nop) | + IO_STATE( R_TIMER_CTRL, tm0, stop_ld) | + IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz); + + *R_TIMER_CTRL = r_timer_ctrl_shadow = + IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) | + IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) | + IO_STATE( R_TIMER_CTRL, i1, nop) | + IO_STATE( R_TIMER_CTRL, tm1, run) | + IO_STATE( R_TIMER_CTRL, clksel1, cascade0) | + IO_STATE( R_TIMER_CTRL, i0, nop) | + IO_STATE( R_TIMER_CTRL, tm0, run) | + IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz); +#else + *R_TIMER_CTRL = + IO_FIELD(R_TIMER_CTRL, timerdiv1, 192) | + IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV) | + IO_STATE(R_TIMER_CTRL, i1, nop) | + IO_STATE(R_TIMER_CTRL, tm1, stop_ld) | + IO_STATE(R_TIMER_CTRL, clksel1, c19k2Hz) | + IO_STATE(R_TIMER_CTRL, i0, nop) | + IO_STATE(R_TIMER_CTRL, tm0, stop_ld) | + IO_STATE(R_TIMER_CTRL, clksel0, flexible); + + *R_TIMER_CTRL = r_timer_ctrl_shadow = + IO_FIELD(R_TIMER_CTRL, timerdiv1, 192) | + IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV) | + IO_STATE(R_TIMER_CTRL, i1, nop) | + IO_STATE(R_TIMER_CTRL, tm1, run) | + IO_STATE(R_TIMER_CTRL, clksel1, c19k2Hz) | + IO_STATE(R_TIMER_CTRL, i0, nop) | + IO_STATE(R_TIMER_CTRL, tm0, run) | + IO_STATE(R_TIMER_CTRL, clksel0, flexible); + + *R_TIMER_PRESCALE = PRESCALE_VALUE; +#endif + + /* unmask the timer irq */ + *R_IRQ_MASK0_SET = IO_STATE(R_IRQ_MASK0_SET, timer0, set); + + /* now actually register the irq handler that calls timer_interrupt() */ + setup_irq(2, &irq2); /* irq 2 is the timer0 irq in etrax */ + + /* enable watchdog if we should use one */ +#if defined(CONFIG_ETRAX_WATCHDOG) + printk("Enabling watchdog...\n"); + start_watchdog(); + + /* If we use the hardware watchdog, we want to trap it as an NMI + and dump registers before it resets us. For this to happen, we + must set the "m" NMI enable flag (which once set, is unset only + when an NMI is taken). + + The same goes for the external NMI, but that doesn't have any + driver or infrastructure support yet. */ + asm ("setf m"); + + *R_IRQ_MASK0_SET = IO_STATE(R_IRQ_MASK0_SET, watchdog_nmi, set); + *R_VECT_MASK_SET = IO_STATE(R_VECT_MASK_SET, nmi, set); +#endif +} |